The trend of future semiconductor packaging process development is toward high precision processes for high power, high density, low cost, light, thin, short and small semiconductor devices, and 3D stacked IC technology is one example of such processes. One of the most challenging factors is heat dissipation. Hot spot formed at local high temperature area inside the 3D stacked IC causes heat and stress concentrations which bring a thermal stress issue and hence affect the product reliability. Therefore, the hot spot issue has become a bottleneck of 3D stacked IC technology. Study shows that the hot spot issue may significantly increase the need for chip heat dissipation, such that the thermal resistance of heat dissipation elements needs to be further reduced, e.g. even reduced to one-second to one-third of its current value. As such, the chip often suffers from severe heat dissipation insufficiency. The heat dissipation insufficiency issue in the 3D stacked IC is even severe. With the increase in heat generation density in stacked ICs, the heat generation per unit area is increased accordingly. Therefore, quickly dissipating the heat of the chip out of the tiny interior of the 3D stacked IC is of critically importance.
Thermoelectric elements formed from semiconductor thermoelectric materials do not need any liquid or gas as coolant and have the advantages of continuous work capability, no pollution, no moving parts, no noise, long life, small volume and light weight. Therefore, the thermoelectric elements have been widely used in cooling or heating apparatus. However, traditional thermoelectric elements have a large volume and require a separate power supply circuit. As such, they can only be attached to an outside of the 3D stacked IC, which still cannot effectively help cool the interior high temperature area.